The molar conductivity of a 0.015 M weak acid (HX) at 298 K, measured in a conductivity cell with cell constant of 0.6 cm–1,is 67 S cm2 mol–1,The limiting molar conductivities at infinite dilution of H+ and X– at 298 K are 350 and 410 S cm2 mol–1 respectively. Ignoring activity coefficients, What is the pKa of HX at 298 K?